Researchers said that more sunlight - and therefore higher vitamin D exposure - in the second trimester of pregnancy could explain the effect, but more research is needed.

Researchers said that birth month affects birth weight and when the girl starts puberty, both of which have an impact on overall health in women as adults.

The environment in the womb leads to differences in early life - including before birth - that can influence health in later life. This effect, called as programming, has consequences for development throughout childhood and into adulthood.

The researchers behind the new study, from the Medical Research Council (MRC) Epidemiology Unit, University of Cambridge, UK, looked at whether birth month had an effect on birth weight, onset of puberty, and adult height.

They found that children who were born in the summer were slightly heavier at birth, taller as adults and went through puberty slightly later than those born in winter months.

"When you were conceived and born occurs largely 'at random' - it's not affected by social class, your parents' ages or their health - so looking for patterns with birth month is a powerful study design to identify influences of the environment before birth," said Dr John Perry, lead author of the study.

The study compared the growth and development of around 450,000 men and women from the UK Biobank study, a major national health resource that provides data on UK volunteers to shed light on the development of diseases.